Essentially it is a file with certain storage provisions which, combined, permit the file's contents to be arranged any-which-way, and in any number of ways at once- Nelson, page 97
My hard-drive, equipped with an operating system, is such a file, and while it may not contain miniscule slides for projection (and I did chuckle a bit when Nelson quipped that CRT consoles "far outshine desktop projectors", as they remain perhaps the hokiest relic of the pre-flatpanel era, seen in older science fiction films such as Blade Runner), it contains an even more space efficient encoding of bits that represent the data to be filed away. This file system is completely customizable, and unique to different users of the same machine. Inter-linking of different lists is easily achieved with aliases or copies of files and pointers. Bush's memex is more like the Apple II of pre-personal computer file systems - it is autonomous and selfish with its information, unable to connect and share with other memex's. Unlike the memex, the personal computer need not contain all the information of an encyclopedia within it's hard-drive; as long as it has an internet connection it can partake in the copious amounts of shared information. Suddenly (or, rather gradually), information isn't power. With Google's success, we can see that cataloguing and utilizing information is power.
The customization of one's desktop environment could even be seen as or compared to the shaping of a Foucault heterotopia. Journal entries, work, notes and other personal information find their way onto one's computer. Even identity theft can be achieved by stealing a few strings of characters off a person's computer (or internet account). These finite numbers are enough to steal someone's identity (or at least as much identity as can possibly be stolen), and convince others (people and machines) that the bearer of such information is truly the rightful owner. As I type this I can glance at a black and white, foggy, faux-artsy cliff that I chose as my desktop 'wallpaper' while my favorite music plays in the background. As soon as my web browser launches I'm greeted with a familiar page and a list of my favorite "spots" to go to on the web. I've forged (or willingly entered) my own heterotopia that can remain autonomous or commune with other heterotopias.
My own file system is merely a restricted branch of the grander file system of the internet, much like how my customized desktop environment is merely a sub-heterotopia of the network with which it communicates. Either way, I hope Nelson and Bush are satisfied with the progress of information catalogues.